1. Field of the Invention
The present invention relates to a light source device using fluorescence obtained by condensing lights from a number of solid-state light sources and exciting a phosphor, and a projection display apparatus using the light source device.
2. Description of Related Art
Discharge lamps have been used widely as light sources for projection display apparatuses using light valves formed of liquid crystals or a mirror-deflection type digital micro-mirror devices (DMD). However, the problem of such a discharge lamp is the low reliability due to the short life. For solving this problem, a projection display apparatus, which uses a solid-state light source such as a semiconductor laser and a light-emitting diode for the light source in place of the discharge lamp, has been studied.
FIG. 8 shows a configuration disclosed in JP 2004-341105 A as an example of a conventional projection display apparatus using a solid-state light source and DMD. Ultraviolet light from a light-emitting diode 101 enters disc-like color wheel 102. On the color wheel 102, a reflective film that transmits the ultraviolet light and reflects visible light is formed. The exiting-side surface of the reflective film is divided in the circumferential direction of the disc into three regions, and red, green and blue phosphor layers are formed on the respective regions, so that red, green and blue color lights are emitted due to the incident ultraviolet light. The emitted lights pass through a relay lens 103, which are reflected by a reflection mirror 104, and reflected by a prism 105, thereby entering a DMD 106. The light entering the DMD 106 is spatially modulated by the DMD 106 in accordance with the video signal, and the modulated light is magnified and projected by a projection lens 107.
A typical solid-state light sources such as a semiconductor laser and a light-emitting diode emits a smaller amount of light beams in comparison with a discharge lamp. Therefore, it is difficult to obtain a high brightness with the configuration as illustrated in FIG. 8. With regard to this circumstance, a potential method of improving the brightness of a light source device using a solid-state light source is to excite a phosphor by using a number of solid-state light sources so as to emit fluorescence, thereby increasing the light beams.